Enable release pipeline on pull requests but don't push images

only push the resulting docker images if the CI job was not triggered on
a pull request (e.g. push to a release branch or manually triggered)

.github/workflows/release.yml

@@ -2,6 +2,7 @@ name: Release
 
 on:
   workflow_dispatch:
+  pull_request:
   push:
     branches:
       - "release/*"
@@ -36,7 +37,7 @@ jobs:
         with:
           context: .
           file: docker/devnet.dockerfile
-          push: true
+          push: ${{ github.event_name != 'pull_request' }}
           tags: gluwa/crunch:devnet-${{github.run_id}}
 
   testnet:
@@ -69,7 +70,7 @@ jobs:
         with:
           context: .
           file: docker/testnet.dockerfile
-          push: true
+          push: ${{ github.event_name != 'pull_request' }}
           tags: gluwa/crunch:testnet-${{github.run_id}}
 
   mainnet:
@@ -105,5 +106,5 @@ jobs:
         with:
           context: .
           file: docker/mainnet.dockerfile
-          push: true
+          push: ${{ github.event_name != 'pull_request' }}
           tags: gluwa/crunch:mainnet-${{github.run_id}}